CEREBELLUM CEREBELLUM Anterior lobe (spinal) Posterior lobe ( - - PDF document

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CEREBELLUM

Meds 5371‐ System Neuroscience

• D. L. Oliver

CEREBELLUM

Posterior lobe ( b l) Anterior lobe (spinal) (cerebral)

Medial View of Cerebellum

Flocculonodular lobe (vestibular)

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Ventral View of Cerebellum

Flocculus

Vermis

Figure 19.1 Overall organization and subdivisions of the cerebellum (Part 4)

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Superior

Cerebellar Peduncles

Middle Inferior

Gross Anatomy of Cerebellum

Cerebellar cortex

• Lateral cortex

Vermis, spinal Paravermis Paravermis

Deep nuclei

• Fastigial
• Interposed
• Dentate Nuc

Folia, like branches

• f a tree

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Basic Cerebellar Circuit

• CEREBELLAR CORTEX

modulates (inhibits) the activity of the DEEP NUCLEI NUCLEI

• Vestibulo-Cerebellum

 Inputs / Outputs with

vestibular system

• Spino-Cerebellum

 Inputs / Outputs with

reticular formation - reticulospinal tract

• Cerebro-Cerebellum

 Inputs /Outputs with

cerebral cortex via pontine nuc and thalamus

Figure 19.3 Functional organization of the inputs to the cerebellum (Part 1)

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Figure 19.3 Functional organization of the inputs to the cerebellum (Part 2)

VESTIBULO- CEREBELLUM

INPUT – Vestibular ganglia AND vestibular nuclei

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G C

Dorsal spinocerebellar Tract

CST Dorsal spinocerebellar tract travels in lateral column to the cerebellum. Carries information about muscle stretch and contraction.

Figure 19.5 Somatotopic maps of the body surface in the cerebellum

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INPUT: P ti Pontine Nucleus

Cerebro-cerebellum

Figure 19.6 Functional organization of cerebellar ouputs

Summary of Cerebellar Outputs

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Figure 19.8 Functional organization of the major descending outputs from the cerebellum (Part 1)

Descending Projections

• f Cerebellum

Figure 19.8 Functional organization of the major descending outputs from the cerebellum (Part 2)

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Output: Fastigial nucleus projects output to vestibular nucleus Output: Flocculus, Fastigio-bulbar tract , nodulus, and vermis project directly to vestibular nucleus

VESTIBULO- CEREBELLUM

Fastigial Nucleus

Spinocerebellum Descending

Fastigio-bulbar tract

OUTPUT- to Reticular Formation. Influence the reticulospinal tract.

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Figure 19.7 Functional organization of the major ascending outputs from the cerebellum (Part 1)

Ascending Projections of Cerebellum

Figure 19.7 Functional organization of the major ascending outputs from the cerebellum (Part 2)

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OUTPUT: Interposed Nuclei

Spinocerebellum Ascending

Superior Cerebellar Peduncle (Brachium Conjunctivum)

Spinocerebellum Ascending

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Spinocerebellum Ascending

OUTPUT: Termination in Red Nucleus; Influence the Rubrospinal tract.

OUTPUT: Dentate Nucleus

Cerebro-cerebellum

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VL

Cerebro-cerebellum

Target: The VA-VL nuclei of the dorsal thalamus that project to motor cortex. Influences corticospinal tract. Other parts of dentate nucleus go to other thalamic nuclei and influence other parts of frontal lobe.

Cerebellar Cortex in Rat

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Cerebellar Cortex Neuron types in cerebellum

• In situ hybridization

for VGAT, GABA transporter

• Top:

 A‐Purkinje  B‐Basket or stellate  C‐Golgi

VGAT

• In situ hybridization

VGLUT1

for VGLUT1, glutamate transporter

• Bottom:

– A‐Granule – B‐White matter

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Figure 19.9 A cerebellar Purkinje neuron in a living slice from mouse cerebellum

(+) GLU

Climbing Fiber input to Purkinje Cell

Purkinje Cell (PC)

1. Origin – Inferior olive 2. Course – Restiform body (inferior cerebellar peduncle)

Climbing fibers (CF)

(inferior cerebellar peduncle) 3. Laterality – Crossed 4. Topographical Organization - Yes 5. Destination – Purkinje cell of Cerebellar cortex

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(+) GLU Granule Cell Parallel Fiber (PF) (+)

Parallel Fiber Input to Purkinje Cell

(GrC) (+) GLU Purkinje Cell (PC) Mossy Fiber (MF) Golgi Cell GABA (-) Feed-back Basket Cell GABA (-) Feed-forward

GABA Interneurons

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Basic Circuit of Cerebellum

• Inputs to

cerebellar cortex are climbing and fib mossy fibers

• Purkinje cells

from cerebellar cortex inhibit the neurons of deep nuclei.

• Deep Nuclei

project to targets targets (outside the cerebellum) that control

• ne of four

major motor tracts.

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Groups of Parallel Fibers Link Groups of Purkinje Cells

Parallel Fiber (PF) Only MF & PF Active During Previously Learned Movement (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) (-) (+) Mossy Fiber (MF) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+)

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LTD at Purkinje Cell

Both CF and MF/PF Systems are Active During a New Movement

Parallel fiber fire (PF) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) Coincident firing

• f parallel fibers

and climbing fibers causes (+) (+) Climbing fiber fires (CF) (-) (+) (+) (-) LTD at parallel fiber synapse More excitation on targets (+) from deep cerebellar nuclei Mossy Fiber (MF) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+) (+)